Bug Fixes:
* Suppress errors when closing local/remote processes. Since the command has completed it is counterproductive to throw an error but still warn to indicate that something unusual happened. (Reviewed by Cynthia Shang. Reported by argdenis.)
* Fix issue with = character in file or database names. (Reviewed by Bastian Wegge, Cynthia Shang. Reported by Brad Nicholson, Bastian Wegge.)
Features:
* Automatically retrieve temporary S3 credentials on AWS instances. (Contributed by David Steele, Stephen Frost. Reviewed by Cynthia Shang, David Youatt, Aleš Zelený, Jeanette Bromage.)
* Add archive-mode option to disable archiving on restore. (Reviewed by Stephen Frost. Suggested by Stephen Frost.)
Improvements:
* PostgreSQL 13 beta3 support. Changes to the control/catalog/WAL versions in subsequent betas may break compatibility but pgBackRest will be updated with each release to keep pace.
* Asynchronous list/remove for S3/Azure storage. (Reviewed by Cynthia Shang, Stephen Frost.)
* Improve memory usage of unlogged relation detection in manifest build. (Reviewed by Cynthia Shang, Stephen Frost, Brad Nicholson, Oscar. Suggested by Oscar, Brad Nicholson.)
* Proactively close file descriptors after forking async process. (Reviewed by Stephen Frost, Cynthia Shang.)
* Delay backup remote connection close until after archive check. (Contributed by Floris van Nee. Reviewed by David Steele.)
* Improve detailed error output. (Reviewed by Cynthia Shang.)
* Improve TLS error reporting. (Reviewed by Cynthia Shang, Stephen Frost.)
Documentation Bug Fixes:
* Add none to compress-type option reference and fix example. (Reported by Ugo Bellavance, Don Seiler.)
* Add missing azure type in repo-type option reference. (Fixed by Don Seiler. Reviewed by David Steele.)
* Fix typo in repo-cipher-type option reference. (Fixed by Don Seiler. Reviewed by David Steele.)
Documentation Improvements:
* Clarify that expire must be run regularly when expire-auto is disabled. (Reviewed by Douglas J Hunley. Suggested by Douglas J Hunley.)
When restoring a cluster that will be promoted but is not intended to be the new primary, it is important to disable archiving to avoid polluting the repository with useless WAL. This option makes disabling archiving a bit easier.
Automatically retrieve the role and temporary credentials for S3 when the AWS instance is associated with an IAM role. Credentials are automatically updated when they are <= 5 minutes from expiring.
Basic configuration is to set repo1-s3-key-type=auto. repo1-s3-role can be used to set a specific role, otherwise it will be retrieved automatically.
Add more info (command, version, options) to asserts, and errors when debug logging is enabled. This won't cover all cases but might mean we get more info in some circumstances.
Currently each module that needs to collect statistics implements custom code to do so. This is cumbersome.
Create a general purpose module for collecting and reporting statistics. Statistics are output in the log at detail level, but there are other uses they could be put to eventually.
No new functionality is added. This is just a drop-in replacement for the current statistics, with the advantage of being more flexible.
The new stats are slower because they involve a list lookup, but performance testing shows stats can be updated at about 40,000/ms which seems fast enough for our purposes.
Improve the performance of list/delete operations by using async requests.
It's questionable whether this will have any impact on Azure deletes since they are sent one at a time with little work done in between, but it doesn't hurt to try.
HTTP/1.0 connections are closed by default after a single response. Other than that, treat 1.0 the same as 1.1.
HTTP/1.0 allows different date formats that we can't parse but for now, at least, we don't need any date headers from 1.0 requests.
Following up on 111d33c, implement the new interfaces for socket client/session. Now HTTP objects can be used over TLS or plain sockets.
This required adding ioSessionFd() and ioSessionRole() to provide the functionality of sckSessionFd() and sckSessionType(). sckClientHost() and sckClientPort don't make sense in a generic interface so they were replaced with ioSessionName().
Only close the remote connection after verifying that the WAL files have been received. This is necessary if the archive_command on the PostgreSQL host is conditional, i.e. archiving only happens while a backup lock is held, to ensure all WAL segments are archived.
Move sckSessionReadyRead()/Write() into the IoRead/IoWrite interfaces. This is a more logical place for them and the alternative would be to add them to the IoSession interface, which does not seem like a good idea.
This is mostly a refactor, but a big change is the select() logic in fdRead.c has been replaced by ioReadReady(). This was duplicated code that was being used by our protocol but not TLS. Since we have not had any problems with requiring poll() in the field this seems like a good time to remove our dependence on select().
Also, IoFdWrite now requires a timeout so update where required, mostly in the tests.
These interfaces allow the HttpClient and HttpSession objects to work with protocols other than TLS, .e.g. plain sockets. This is necessary to allow standard HTTP -- right now only HTTPS is allowed, i.e. HTTP over TLS.
For now only TlsClient and TlsSession have been converted to the new interfaces. SocketClient and SocketSession will also need to be converted but first sckSessionReadyRead() and sckSessionReadyWrite() need to be moved into the IoRead and IoWrite interfaces, since they are not a good fit for IoSession.
Before 9f2d647 TLS errors included additional details in at least some cases. After 9f2d647 a connection to an HTTP server threw `TLS error [1]` instead of `unable to negotiate TLS connection: [336031996] unknown protocol`.
Bring back the detailed messages to make debugging TLS errors easier. Since the error routine is now generic the `unable to negotiate TLS connection context` is not available so the error looks like `TLS error [1:336031996] unknown protocol`.
PostgreSQL may be using most of the available file descriptors when it executes the the archive-get/archive-push commands (especially archive-get). This can lead to problems depending on how many file descriptors are needed for parallelism in the async process.
Proactively free file descriptors between 3 and 1023 to help ensure there are enough available for reasonable values of process-max, i.e. <= 300.
This loop was using a lot of memory without freeing it at intervals.
Rewrite to use char arrays when possible to reduce memory that needs to be allocated and freed.
The fix for = characters in info files (039d314) added JSON validation but discarded the resulting Variant which means the JSON is being parsed twice. This nearly doubles the time to load a manifest since a lot of complex JSON is involved.
Time to load a million file manifest:
Before 039d314: 7.8s
039d314: 15.5s
This patch: 7.5s
To fix this regression return the Variant in the callback so the caller does not have to parse it again. The new code appears slightly more efficient overall, probably because there are fewer operations against Strings.
We use the Z suffix in many functions to indicate that we are expecting a zero-terminated string so make this function conform to the pattern.
As a bonus the new name is a bit shorter, which is a good quality in a commonly-used function.
The manifest uses the = character as the key/value separator so = characters in the key cause parsing errors and lead to an error or segfault.
Since the value must be valid JSON we can keep checking the value on the right side of the = and stop building the key when the value is valid. It's a bit hackish but it does seem to do the job without breaking the manifest format.
Unsurprisingly this makes parsing about 50% slower but it's still more than fast enough. Parsing 10 million key/values takes about 6.5s for the old code and 10s for the new code. Since the value is used as JSON downstream we can reclaim most of this time by just passing the JSON value rather than making the callback reparse it. We'll save that for another commit, though.
Since the command has completed it is counterproductive to throw an error but still warn to indicate that something unusual happened.
Also fix the related issue that the local processes were not being shut down when they completed, which meant that they might timeout before being closed when pgbackrest terminated.
Also update the policy in doc/RELEASE.md to get the latest versions at the beginning of the release cycle. The older policy was created when we were getting new versions right before the release.
Bug Fixes:
* Fix restore --force acting like --force --delta. This caused restore to replace files based on timestamp and size rather than overwriting, which meant some files that should have been updated were left unchanged. Normal restore and restore --delta were not affected by this issue. (Reviewed by Cynthia Shang.)
Features:
* Azure support for repository storage. (Reviewed by Cynthia Shang, Don Seiler.)
* Add expire-auto option. This allows automatic expiration after a successful backup to be disabled. (Contributed by Stefan Fercot. Reviewed by Cynthia Shang, David Steele.)
Improvements:
* Asynchronous S3 multipart upload. (Reviewed by Stephen Frost.)
* Automatic retry for backup, restore, archive-get, and archive-push. (Reviewed by Cynthia Shang.)
* Disable query parallelism in PostgreSQL sessions used for backup control. (Reviewed by Stefan Fercot.)
* PostgreSQL 13 beta2 support. Changes to the control/catalog/WAL versions in subsequent betas may break compatibility but pgBackRest will be updated with each release to keep pace.
* Improve handling of invalid HTTP response status. (Reviewed by Cynthia Shang.)
* Improve error when pg1-path option missing for archive-get command. (Reviewed by Cynthia Shang.)
* Add hint when checksum delta is enabled after a timeline switch. (Reviewed by Matt Bunter, Cynthia Shang.)
* Use PostgreSQL instead of postmaster where appropriate. (Reviewed by Cynthia Shang.)
Documentation Bug Fixes:
* Fix incorrect example for repo-retention-full-type option. (Reported by Höseyin Sönmez.)
* Remove internal commands from HTML and man command references. (Reported by Cynthia Shang.)
Documentation Improvements:
* Update PostgreSQL versions used to build user guides. Also add version ranges to indicate that a user guide is accurate for a range of PostgreSQL versions even if it was built for a specific version. (Reviewed by Stephen Frost.)
* Update FAQ for expiring a specific backup set. (Contributed by Cynthia Shang. Reviewed by David Steele.)
* Update FAQ to clarify default PITR behavior. (Contributed by Cynthia Shang. Reviewed by David Steele.)
The postgresql.auto.conf file was being used instead of recovery.conf, but there were still instances in the text that used recovery.conf. Update to postgresql.auto.conf for PostgreSQL >= 10 and change wording where needed.
Remove all check and stanza-* tests except for the ones that are intended to succeed. The successful tests show that the queries run with expected results against each version of PG which should also validate queries for the failure tests in the unit tests.
Also remove the tests for --no-online backups since they don't require a database and are well tested in the unit tests.
The prior code was only able to use the main passphrase automatically and expected sub passphrases to be specified for each operation. This was fine for testing but hardly sufficient for a user-facing feature.
Update the code to determine which passphrase to use for any file in the repository and error when an invalid file or location is selected.
The repo-get command is still internal for now, but with this improvement it should be ready to be made public.
If a local command, e.g. backupFile(), fails it will stop the entire process. Instead, retry local commands to deal with transient errors.
Remove special logic in the S3 storage driver to retry RequestTimeTooSkewed errors since this is now handled by the general retry mechanism in the places where it is most likely to happen, i.e. file read/write. Also, this error should have been entirely eliminated by the asynchronous TLS implementation.
A shared access signature (SAS) provides granular, delegated access to resources in a storage account. This is often preferable to using a shared key which provides more access and is a greater security risk if compromised.
This caused restore to replace files based on timestamp and size rather than overwriting, which meant some files that should have been updated were left unchanged. Normal restore and restore --delta were not affected by this issue.
Azure and Azure-compatible object stores can now be used for repository storage.
Currently only shared key authentication is supported but SAS will be added soon.
There don't appear to be any behavioral changes since PostgreSQL 12 and all the tests pass.
Changes to the control/catalog/WAL versions in subsequent betas may break compatibility but pgBackRest will be updated with each release to keep pace.
There is no need to have parallelism enabled in a backup control session. In particular, 9.6 marks pg_stop_backup() as parallel-safe but an error will be thrown if pg_stop_backup() is run in a worker.
When uploading large files the upload is split into multiple parts which are assembled at the end to create the final file. Previously we waited until each part was acknowledged before starting on the processing (i.e. compression, etc.) of the next part.
Now, the request for each part is sent while processing continues and the response is read just before sending the request for the next part. This asynchronous method allows us to continue processing while the S3 server formulates a response.
Testing from outside AWS in a high-bandwidth, low-latency environment showed a 35% improvement in the upload time of 1GB files. The time spent waiting for multipart notifications was reduced by ~300% (this measurement included the final part which is not uploaded asynchronously).
There are still some possible improvements: 1) the creation of the multipart id could be made asynchronous when it looks like the upload will need to be multipart (this may incur cost if the upload turns out not to be multipart). 2) allow more than one async request (this will use more memory).
A fair amount of refactoring was required to make the HTTP responses asynchronous. This may seem like overkill but having well-defined request, response, and session objects will also be advantageous for the upcoming HTTP server functionality.
Another advantage is that the lifecycle of an HttpSession is better defined. We only want to reuse sessions that complete the request/response cycle successfully, otherwise we consider the session to be in a bad state and would prefer to start clean with a new one. Previously, this required complex notifications to mark a session as "successfully done". Now, ownership of the session is passed to the request and then the response and only returned to the client after a successful response. If an error occurs anywhere along the way the session will be automatically closed by the object destructor when the request/response object is freed (depending on which one currently owns the session).
strPtr() is called more than any other function and during profiling (with or without optimization) it can end up using a disproportionate amount of the total runtime. Even though it is fast, the profiler has a minimum resolution for each function call so strPtr() will often end up towards the top of the list even though the real runtime is quite small.
Instead, inline strPtr() and indicate to gcc that it should be inlined even for non-optimized builds, since that's how profiles are usually generated.
To make strPtr() smaller require "this" to be non-NULL and add another function, strPtrNull(), to deal with the few cases where we need NULL handling.
As a bonus this makes the executable about 1% smaller even when compared to a prior optimized build which would inline some percentage of strPtr() calls.
This aligns better with general PostgreSQL usage and our own documentation (updated in 4bcef702).
Usage in the backup.manifest tests has not been updated since it might break the file format.
Expressions only worked at the first level of recursion because the expression was also being applied to paths so the path had to match the filter in order to recurse.
This is not considered a bug since it does not affect any existing code paths, but it is required for the general-purpose repo-ls command.
A truncated HTTP response status could lead to an an unfriendly error message, which would be retried, but could be confusing if the error was persistent and required debugging.
Improve the error handling overall to catch more error cases explicitly and respond better to edge cases.
Also update the terminology in comments to align with the RFC. Variable and function names were not changed because a refactor is intended for HTTP response and it doesn't seem worth the additional code churn.
Bug Fixes:
* Fix issue checking if file links are contained in path links. (Reviewed by Cynthia Shang. Reported by Christophe Cavallié.)
* Allow pg-path1 to be optional for synchronous archive-push. (Reviewed by Cynthia Shang. Reported by Jerome Peng.)
* The expire command now checks if a stop file is present. (Fixed by Cynthia Shang. Reviewed by David Steele.)
* Handle missing reason phrase in HTTP response. (Reviewed by Cynthia Shang. Reported by Tenuun.)
* Increase buffer size for lz4 compression flush. (Reviewed by Cynthia Shang. Reported by Eric Radman.)
* Ignore pg-host* and repo-host* options for the remote command. (Reviewed by Cynthia Shang. Reported by Pavel Suderevsky.)
* Fix possibly missing pg1-* options for the remote command. (Reviewed by Cynthia Shang. Reported by Andrew L'Ecuyer.)
Features:
* Time-based retention for full backups. The --repo-retention-full-type option allows retention of full backups based on a time period, specified in days. (Contributed by Cynthia Shang, Pierre Ducroquet. Reviewed by David Steele.)
* Ad hoc backup expiration. Allow the user to remove a specified backup regardless of retention settings. (Contributed by Cynthia Shang. Reviewed by David Steele.)
* Zstandard compression support. Note that setting compress-type=zst will make new backups and archive incompatible (unrestorable) with prior versions of pgBackRest. (Reviewed by Cynthia Shang.)
* bzip2 compression support. Note that setting compress-type=bz2 will make new backups and archive incompatible (unrestorable) with prior versions of pgBackRest. (Contributed by Stephen Frost. Reviewed by David Steele, Cynthia Shang.)
* Add backup/expire running status to the info command. (Contributed by Stefan Fercot. Reviewed by David Steele.)
Improvements:
* Expire WAL archive only when repo-retention-archive threshold is met. WAL prior to the first full backup was previously expired after the first full backup. Now it is preserved according to retention settings. (Contributed by Cynthia Shang. Reviewed by David Steele.)
* Add local MD5 implementation so S3 works when FIPS is enabled. (Reviewed by Cynthia Shang, Stephen Frost. Suggested by Brian Almeida, John Kelley.)
* PostgreSQL 13 beta1 support. Changes to the control/catalog/WAL versions in subsequent betas may break compatibility but pgBackRest will be updated with each release to keep pace. (Reviewed by Cynthia Shang.)
* Reduce buffer-size default to 1MiB. (Reviewed by Stephen Frost.)
* Throw user-friendly error if expire is not run on repository host. (Contributed by Cynthia Shang. Reviewed by David Steele.)
The purpose of the remote command is to get access to local resources, so a remote should never start another remote. However, this could happen if there were host settings on the remote host, which ended badly with lock errors, loops, etc.
Add pg-local and repo-local options to indicate that the resource is local even if there are host settings.
Note that for the time being these options are internal and not intended for general usage. However, this is likely the direction needed to allow for more symmetric and manageable configurations.
Some pg1-* options are required by the remote so if they are not provided in the remote's configuration file then it may cause a configuration error, depending on the operation. This currently only applies to the pg1-path option.
This is still an issue for repo-* options but the same solution cannot be applied because some repo-* options are secure and cannot be passed on the command-line.
There don't appear to be any behavioral changes since PostgreSQL 12 and all the tests pass.
Changes to the control/catalog/WAL versions in subsequent betas may break compatibility but pgBackRest will be updated with each release to keep pace.
S3 requires the Content-MD5 header for many requests but MD5 is not available via OpenSSL when FIPS is enabled because it is considered to be insecure.
Even though our usage does not present any security risks a local M5 implementation is required to circumvent the over-broad FIPS restriction.
Vendorize the MD5 implementation found at https://openwall.info/wiki/people/solar/software/public-domain-source-code/md5 and add full coverage for the module in the common/crypto unit tests.
The prior default was determined by benchmarking the Perl code prior to the 1.0 release. In general buffer allocation was more expensive in Perl so large buffers gave the best performance. This was due to multiple buffer allocations for each filter in an IO operation.
The C code allocates fixed buffers for each IO operation so the cost for buffer allocation is lower than Perl. That being the case it made sense to benchmark the C code to determine the optimal buffer default.
The performance/storage tests were used to measure the performance of a variety of filters. 1GiB of data was processed by each filter 10 times and the results of the tests were averaged.
While most buffer sizes gave similar performance, 1MiB appeared to perform the best overall. Of course, different architectures are likely to yield different results but this seems like a sensible default. The buffer-size option may still need to be manually configured to give optimal results.
Raw test data for reference:
4MB buffer (prior default)
copy time 1807ms, avg time 180ms, avg throughput: 5942MB/s
md5 time 14200ms, avg time 1420ms, avg throughput: 756MB/s
sha1 time 11431ms, avg time 1143ms, avg throughput: 939MB/s
sha256 time 23463ms, avg time 2346ms, avg throughput: 457MB/s
gzip -6 time 381199ms, avg time 38119ms, avg throughput: 28MB/s
lz4 -1 time 15484ms, avg time 1548ms, avg throughput: 693MB/s
1MB buffer (new default)
copy time 1760ms, avg time 176ms, avg throughput: 6100MB/s
md5 time 13739ms, avg time 1373ms, avg throughput: 781MB/s
sha1 time 11025ms, avg time 1102ms, avg throughput: 973MB/s
sha256 time 22539ms, avg time 2253ms, avg throughput: 476MB/s
gzip -6 time 372995ms, avg time 37299ms, avg throughput: 28MB/s
lz4 -1 time 15118ms, avg time 1511ms, avg throughput: 710MB/s
512K buffer
copy time 1782ms, avg time 178ms, avg throughput: 6025MB/s
md5 time 13724ms, avg time 1372ms, avg throughput: 782MB/s
sha1 time 10959ms, avg time 1095ms, avg throughput: 979MB/s
sha256 time 22982ms, avg time 2298ms, avg throughput: 467MB/s
gzip -6 time 378120ms, avg time 37812ms, avg throughput: 28MB/s
lz4 -1 time 15484ms, avg time 1548ms, avg throughput: 693MB/s
256K buffer
copy time 1805ms, avg time 180ms, avg throughput: 5948MB/s
md5 time 13706ms, avg time 1370ms, avg throughput: 783MB/s
sha1 time 11074ms, avg time 1107ms, avg throughput: 969MB/s
sha256 time 22588ms, avg time 2258ms, avg throughput: 475MB/s
gzip -6 time 372645ms, avg time 37264ms, avg throughput: 28MB/s
lz4 -1 time 16346ms, avg time 1634ms, avg throughput: 656MB/s
Reason phrases (e.g. OK) are optional in HTTP 1.1 but the space after the status code is not. When the reason phrase was missing the required space was trimmed along with the trailing CR leading to a format error.
Rework the logic to preserve the space and allow empty reason phrases.
Found while testing against the Backblaze S3-compatible API.
Some lz4 versions between r131 and 1.7.5 did not return a sufficient buffer size from LZ4F_compressBound() to allow LZ4F_compressEnd() to complete reliably. While this issue was fixed in lz4 1.7.5 there are affected versions in supported distributions such as CentOS/RHEL 7.
Use one of the hacks suggested in https://github.com/lz4/lz4/issues/290 to increase the buffer size enough for LZ4F_compressEnd() to complete. This means that a slightly larger buffer size is required for all versions but it seems worth it to (hopefully) to fix the issue in all lz4 versions.
Update error types throw by bzip2 to be more consistent with gzip.
Update the bzip2 and gzip error default to be AssertError as that's the more common case in both, and add a 'break;' to the default clause -- we don't intend to be just falling through those case statements, even if the default is the last, we should be explicit about that.
Clean up some tabs that snuck in, rename a variable to be more clear, and add some comments.
The --repo-retention-full-type option allows retention of full backups based on a time period, specified in days.
The new option will default to 'count' and therefore will not affect current installations. Setting repo-retention-full-type to 'time' will allow the user to use a time period, in days, to indicate full backup retention. Using this method, a full backup can be expired only if the time the backup completed is older than the number of days set with repo-retention-full (calculated from the moment the 'expire' command is run) and at least one full backup meets the retention period. If archive retention has not been configured, then the default settings will expire archives that are prior to the oldest retained full backup. For example, if there are three full backups ending in times that are 25 days old (F1), 20 days old (F2) and 10 days old (F3), then if the full retention period is 15 days, then only F1 will be expired; F2 will be retained because F1 is not at least 15 days old.
Newer versions of sudo output this message to stdout when run in a container:
sudo: setrlimit(RLIMIT_CORE): Operation not permitted
See https://github.com/sudo-project/sudo/issues/42 for details.
A simple workaround is to prevent sudo from disabling core dumps. This seems safe enough because if sudo is segfaulting then core files are the least of our worries.
bzip2 is a widely available, high-quality data compressor. It typically compresses files to within 10% to 15% of the best available techniques (the PPM family of statistical compressors), while being around twice as fast at compression and six times faster at decompression.
bzip2 is currently available on all supported platforms.
Zstandard is a fast lossless compression algorithm targeting real-time compression scenarios at zlib-level and better compression ratios. It's backed by a very fast entropy stage, provided by Huff0 and FSE library.
Zstandard version >= 1.0 is required, which is generally only available on newer distributions.
The previous location was too late to allow --var=s3-all=y to work with --require=/repo-host, which depends on /quickstart/configure-archiving.
Since the section is not included in production documentation, the position is not very important to flow so just move it to where it works.
If the WAL path is absolute then pg1-path should be optional but in fact it was required to load pg_control.
Skip the pg_control check when pg1-path is not specified. The check against the stanza version/system-id remains to protect the repo from corruption.
There is no conflict if the path containing a file link is a parent path of a path link. The Perl code apparently had this right but the migration to C missed it.
Exclude this case when checking for link conflicts.
There have been a number of segfaults reported because a string option expected to be non-null was actually null. This is generally due to options that are expected to be set but are in fact optional.
Protect against this by creating cfgOptionStrNull() to get options that can be null, while changing cfgOptionStr() to always expect non-null. There are relatively few places where nulls are expected.
There is definitely a chance for breakage here as null options might currently be working in the field but will be caught by this new check. Hopefully introducing the check early in the release cycle will allow us to catch any issues.
Previously when retention-archive was set (either by the user or by default), archives prior to the archive-start of the oldest remaining full backup (after backup expiration occurred) would be expired even though the retention-archive threshold had not been met. For example, if there were 1 full backup remaining after backup expiration and the retention-archive was set to 2 and retention-archive-type=full, then archives prior to the archive-start of the remaining full backup would still be removed even though retention-archive required 2 full backups remaining before archives should be expired.
The thought was to keep the archive directory clean and since the full backup did not require prior archives, it was safe to delete them. However, this has caused problems for some users in the past (because they needed the WAL for other purposes) and with the new adhoc and time-based retention features, it was decided that the archives should remain until the threshold was met. The archives will eventually be removed and if having them causes space issues, the expire command and the retention-archive can always be run and adjusted.
The specified backup set (i.e. the backup label provided and all of its dependent backups, if any) will be expired regardless of backup retention rules except that at least one full backup must remain in the repository.
This is implemented by checking for a backup lock on the host where info is running so there are a few limitations:
* It is not currently possible to know which command is running: backup, expire, or stanza-*. The stanza commands are very unlikely to be running so it's pretty safe to guess backup/expire. Command information may be added to the lock file to improve the accuracy of the reported command.
* If the info command is run on a host that is not participating in the backup, e.g. a standby, then there will be no backup lock. This seems like a minor limitation since running info on the repo or primary host is preferred.
Bug Fixes:
* Remove empty subexpression from manifest regular expression. MacOS was not happy about this though other platforms seemed to work fine. (Fixed by David Raftis.)
Improvements:
* Non-blocking TLS implementation. (Reviewed by Slava Moudry, Cynthia Shang, Stephen Frost.)
* Only limit backup copy size for WAL-logged files. The prior behavior could possibly lead to postgresql.conf or postgresql.auto.conf being truncated in the backup. (Reviewed by Cynthia Shang.)
* TCP keep-alive options are configurable. (Suggested by Marc Cousin.)
* Add io-timeout option.
Timeout used for connections and read/write operations.
Note that the entire read/write operation does not need to complete within this timeout but some progress must be made, even if it is only a single byte.
The prior blocking implementation seemed to be prone to locking up on some (especially recent) kernel versions. Since we were unable to reproduce the issue in a development environment we can only speculate as to the cause, but there is a good chance that blocking sockets were the issue or contributed to the issue.
So move to a non-blocking implementation to hopefully clear up these issues. Testing in production environments that were prone to locking shows that the approach is promising and at the very least not a regression.
The main differences from the blocking version are the non-blocking connect() implementation and handling of WANT_READ/WANT_WRITE retries for all SSL*() functions.
Timeouts in the tests needed to be increased because socket connect() and TLS SSL_connect() were not included in the timeout before. The tests don't run any slower, though. In fact, all platforms but Ubuntu 12.04 worked fine with the shorter timeouts.
select() is a bit old-fashioned and cumbersome to use. Since the select() code needed to be modified to handle write ready this seems like a good time to upgrade to poll().
poll() has been around for a long time so there doesn't seem to be any need to provide a fallback to select().
Also change the error on timeout from FileReadError to ProtocolError. This works better for read vs. write and failure to poll() is indicative of a protocol error or unexpected EOF.
The prior behavior introduced in dcddf3a5 could possibly lead to postgresql.conf or postgresql.auto.conf being truncated in the backup since they are copied via tmp files and could change size during the backup.
In general it seems safer to limit this feature to WAL-logged files which will be reconstructed during recovery.
A session looks much the same whether it is initiated from the client or the server, so use the session objects to implement the TLS, HTTP, and S3 test servers.
For TLS, at least, there are some differences between client and server sessions so add a client/server type to SocketSession to determine how the session was initiated.
Aside from reducing code duplication, the main advantage is that the test server will now timeout rather than hanging indefinitely when less input that expected is received.
